Yeah hadn't thought of slugs maybe would promote other pest as well. Would look nice and save on the work load but will toss the idea to the bin. Did find this nice article by a man named Bob Kemp answers the how deep question for me:
Hi --
I thought I'd talk a little about how to grow the tobacco outside in a field now. I've already talked about starting the seeds indoors 6-7 weeks before your first average frost, but what do you need to do in the field to prepare to plant and what about during the growing season?
Picking the field - Tobacco requires full sunlight all day. The location of the field should give the maximum of direct sunlight without shade possible. At the very least, you must have 8 hours of full sunlight. Try to make sure the field isn't on a hillside with an extreme slope unless you are able to control flooding and runoff erosion. Make sure the field isn't in a place where flooding occurs and water is likely to stand. If so, you may need to consider using raised beds. Tobacco does not like to have its feet in standing water.
The first thing to be aware of is that the soil should be well-worked. If it is a new field, then a deep plowing is usually required. This should be done NOW NOW NOW! (early Fall) If you do not have access to a tractor and a plow and are growing a small crop of 150 plants or less, then you can use a heavy garden fork. Go down the row and put the fork as deep in the ground as you can, lever up the soil and turn it over and continue until it is done. After that, till the top 8 inches or so to prepare to put the transplants out in the spring.
Next, it makes good sense to amend the soil almost anywhere you are located with a good composted manure. If you can, get a soil test at your local ag extension and follow their directions for adding nutrients and adjusting the ph. Ideal ph for tobacco is about 6.8, just slightly acidic. If the ph is too low, you can add lime. If it is too high, you can add pelleted sulphur. These amendments are available at a reasonable price at a feed store.
Tobacco does not like highly fertile soil. In fact, the best tobacco quality comes from sandy soils poor in nutrients. You add what the plant needs, just enough for it and no more. Unlike tomatoes which are heavy feeders, tobacco should be fed just enough to grow the leaves you want then starved for nutrients so that it does not store up a lot of nitrogen compounds in the leaves and stems. In this manner, you make it easier to color cure after harvest (I will write a section on curing after harvest later).
Hardening the transplants - About a week before you put them in the field, place them outside during nice weather starting at a couple of hours of light a day and ending up with them in full sunlight. Beware of freezes. Beware of high winds. Beware of the pots completely drying out.
The average tobacco plant is set out 2 feet apart in the row with 3 feet between rows. Some dwarf varieties, such as rustica, can be placed much closer. Some huge varieties should be spaced even further apart. And this is a guidline, if your soil is particularly fertile, you can place them a little closer but remember that the plants each need good light and an 8 foot tall plant will cast quit a shadow! You also will need room to work between the rows! I've had people who used close row spacings complain they can't get into the jungle!
I typically put out the transplants and put about 1/2 cup of Miracle Grow (or other full-nutrient liquid fertilizer equivalent) on each plant. In the hole, before I plant them, I put 1 tsp of epsom salts and a handful of compost and mix it up. Be SURE to plant the transplants deep! You can remove the bottom 2 leaves or so if you like. If the transplant is 6 inches tall, plant at least half of the stem under the ground! Tobacco will root from the stem like tomatoes, and this will give it a much bigger root system faster. It will also reduce the problem of plants falling over in the field later.
One week later, I side dress the plants with a dry fertilizer. The type you will need will depend a lot on your soil test, but if you didn't get one your local feed store will advise you on what is best. Half of the nitrogen should be in a slow release form. You can take a hoe and make a 3-4 inch deep trench about 6 inches from the plants along the row on each side and spread the fertilizer according to the lbs per sq. ft. needed then cover it up.
Watering -- The new transplants will not have an established root system to support the full sunlight. Expect them to wilt during the heat of the day but don't panic! They will usually rehydrate overnight as long as you supply some water to the roots. Water in the morning and never during the full light of the day no matter how wilted they look.
How much water? Overwatering is a bad idea because the plant roots may be drowned. Light watering, but often, is a bad idea because that will only encourage the roots at the top to grow and we want them to reach 10-12 deep as they reach down for the water. Allow the top 3-4 inches of soil to be fairly dried out, then soak them down.
After watering, test the soil with your finger or dig some out with a shovel 6-8 inches deep to check the moisture content deeper in the ground. If it is dry down there, water some more. This should mean you are only required to water the plants every few days at most if you don't get rain during the establishment of the deeper roots. Later in the season, deep roots will allow the plants to be more drought resistant and perhaps irrigation will be unnecessary.
About 6 weeks after you plant them out, side dress again with the same fertilizer. That's all the fertilizer you will need for the year.
Ok, that's a pretty good description of how to get the field ready, to plant and how to get them started. Next I will talk about pests, fungus and weed issues and how to control them. Let me know if you have any questions.
Bob Kemp
